Editor's note: These minutes have not been edited. Multiparty Multimedia Session Control Working Group (MMUSIC) Minutes from the 37th IETF San Jose, California, USA December 9-10, 1996 Chairs Mark Handley, mjh@isi.edu Ruth Lang, rlang@sri.com Eve Schooler, schooler@cs.caltech.edu MMUSIC met during two sessions at the 37th IETF, both of which were multicast. A summary of each of the talks and pointers to relevant Internet-Drafts or related documents is included below. An on-line copy of these minutes and accompanying slides are available from ftp://ftp.isi.edu/confctrl/minutes in the files ietf.12.96 and slides.12.96.{tar, tar.Z}. Individual slide presentations can be obtained from the directory slides.12.96. These notes were prepared by Ruth Lang. Mark Handley (USC/Information Sciences Institute) described the significant modifications made to the Session Description Protocol. See the slides sdp.ps, and the documents ftp://ds.internic.net/internet-drafts/draft-ietf-mmusic-sdp.02.txt ftp://ftp.isi.edu/confctrl/docs/draft-ietf-mmusic-sdp.02.ps These include simplification of time fields, the addition of new attributes (e.g., for the quality of video encodings), and an enhancement of the encryption keys (now an attribute/value pair as an indirection for obtaining keys). He then introduced the topic of representing session capabilities (i.e., options from which to choose to create a session as opposed to an instantiatable session as SDP describes now). A strawman extension to the syntax of SDP was introduced and examples of its use were given. Questions arose from the group which identified that "potential sessions" were not a well-understood concept. Mark proposed that the current draft of SDP be pushed forward as a proposed standard and that work begin to extend SDP to support capability description. Henning Schulzrinne objected to the latter in favor of adopting a new syntax rather than extending SDP itself. He also said that he would raise an objection to the former if advancing the current SDP draft implied that compatibility with it would need to be maintained by a new session description format/protocol. Ross Finlayson (Live Networks, Inc.) spoke briefly about the work of the Calendaring and Scheduling Working Group and identified that isomorphism between a CALSCH event and an event represented in SDP was needed. His input to that group has encouraged them to adopt the use of UTC time, etc. that will make their event descriptions compatible with SDP. He also identified areas of potential incompatibility which implied that participation by MMUSIC in this WG is needed to ensure compatible results. Mark Handley described the significant modifications made to the Session Announcement Protocol. See the slides sap.ps and the documents ftp://ds.internic.net/internet-drafts/draft-ietf-mmusic-sap.00.txt ftp://ds.internic.net/internet-drafts/draft-ietf-mmusic-sap.00.ps (Please note that a previous PostScript-only version of this Internet-Draft existed but the lack of a text version caused the reuse of "00" for the 2nd version of the document). These modifications include removal of a padding bit from the SAP header, the addition of a compression bit for indicating use of gzip (zlib) compression, removal of the address-test message type, and the addition of a key id field. Open issues were identified and discussed which included security, generation of a unique ID (guid's suggested as an option), and restricting SAP to carry only SDP packets. Mark Handley presented a "new" protocol, the Session Initiation Protocol (SIP v2). See the slides sip.ps and the documents ftp://ftp.isi.edu/confctrl/docs/draft-ietf-mmusic-sip-01.txt ftp://ftp.isi.edu/confctrl/docs/draft-ietf-mmusic-sip-01.ps This protocol represents the unification of Handley/Schooler's Session Invitation Protocol (SIP v1) and Schulzrinne's Simple Conference Invitation Protocol (SCIP). (Note that all are co-authors on this new draft.) The new protocol is specified to be carried over UDP or TCP, uses an HTTP-like syntax and HTTP 1.1 status codes. Proxy rules are more tightly defined in SIP v2 but TCP/UDP translation proxies are to be completed. Open issues identified include: supporting capability requests, adding additional support for transfers between telephone and Internet. Pete Cordell of British Telecom presented a description of research work to develop the Simple Universal Call/Conference Establishment Sequence Protocol (SUCCESS). See the slides success.{ppt, ps} and the document ftp://ds.internic.net/internet-drafts/draft-cordell-success-00.txt It is a single protocol for session management (cf the modular approach employed in the specification of MMUSIC protocols) intended to support the range of tightly to loosely controlled sessions. It's call model is based on a "hello-hello" paradigm. Due to lack of time, not much discussion on this protocol ensued. Scott Petrack (Vocaltec, Ltd.) provided an overview of the VoIP (Voice on IP) Forum. See the slides voip.{ppt, ps}. VoIP is an IMTC group whose goal is to ensure and promote industry-wide interoperability of Internet voice communications products. They will define technical guidelines for two-party voice and other audio communications for compatibility with traditional telephone service networks via telephony/IP gateways. Their are currently working on items such as RTP payload formats for DTMF tones and comfort noise, and an agent-based architecture for pre-call setup called Call Management Agents (CMA). Their mailing list is voip-tech@vocaltec.com (requests to voip-tech-requests@vocaltec.com); more information can be obtained from http://www.imtc.org/n/n_whatnu.htm#voip. Rob Lanphier (Progressive Networks) and Anup Rao (Netscape Communication) provided an overview of the Real Time Stream Protocol (RTSP). See the slides rtsp_require.{ppt, ps} and the document ftp://ds.internic.net/internet-drafts/draft-ietf-mmusic-rtsp-00.txt Two examples were presented to illustrate the protocol's use: exchanging version information (see the slides rtsp_eg1.{ppt, ps}) and streaming a multimedia file (see the slides rtsp_eg2.{ppt, ps}). Henning Schulzrinne (Columbia University) provided an overview of RTSP'. See the slides rtsp_prime1.ps (or rtsp_prime6.ps) and the documents ftp://ds.internic.net/internet-drafts/draft-ietf-mmusic-stream.00.txt ftp://ds.internic.net/internet-drafts/draft-ietf-mmusic-stream.00.ps RTSP' is an alternative proposal to RTSP inspired by the Netscape/Progressive work but is more compatible with existing MMUSIC protocols (SDP, SIP v2). Open issues for real-time streaming were discussed which included text vs binary representation of the protocol, stream control vs device control, metafile/session descriptions, joining into existing conferences, multi-client control of streams, and the use of UUIDs as identifiers. Daniel Adam (Microsoft Corp.) volunteered to create a scenario describing the issues surrounding the use of UUIDs through firewalls for future interaction with firewall vendors. Akira Amamo (Hiroshima City University) presented the CamCorder Control Protocol targeted for the control of video cameras and VCRs. See the slides camcorder.{ppt, ps}. The protocol is a text-based protocol designed after ftp. Christian Huitema suggested that the authors consider writing an SNMP MIB for this purpose. A disagreement about the appropriateness of text vs binary for such a protocol was cut short due to lack of time in the session.